Alexander Zverev has the "mental strength" and "gumption" to come out and win the crowd over after upsetting Novak Djokovic at the ATP Finals in what Greg Rusedski has also described as one the "great performances".

We look back through some of the most iconic moments over the years on Sky Sports and in particular, the four icons who changed the game - Roger Federer, Rafael Nadal, Novak Djokovic, and Britain's Andy Murray.

Alexander Zverev ended Roger Federer's season and his hopes of a 100th career title and seventh in London as he reached the final of the season-ending ATP Finals in a dramatic contest at the O2 Arena on Saturday.

Alexander Zverev ended Roger Federer's season and his hopes of a 100th career title and seventh in London as he reached the final of the season-ending ATP Finals in a dramatic contest at the O2 Arena on Saturday.